Green screen / transparent rendering?

[Rik56]

Hi there,
I am looking for a way to create renders with alpha channel (so that the render can be layered later on in post), is it possible? If not, what would be a best way to set up green environment which does not effect the models in it (so they don't get green hue).

I guess another way would be to have the environment white and all the models black, so I can use it as luma matte. But that would require me to change all the materials before render.

Thanks!

[face_off]

Hi - tick the Kernel->Alpha Channel checkbox and then save the render to PNG and load into Photoshop to overlay it on a background image.

Paul

[Rik56]

Thanks, exactly what I was looking for. Now I am looking for a way to set up material so it is not rendered, but still obscures the objects behind it. (basical creates a "hole" in the image). It looks like "shadow catcher" is the option I am looking for, but the invisible materials are still shaded. Is there some way to disable the shadows?

Hopefuly the picture wil make it cleare, this is the result I am looking for, but I would like to get rid of the shadows on the sphere.

[Isotemod]

I don't think there is a 1 step method of producing this effect but if you use the info channel kernel type "render layer ID" and set the objects to the same render layer that you want to be "green" activate the alpha channel then you will have a mask that you can convert the "green" to alpha and load that into your normal renders alpha channel.

[DrHemulen]

I used to do something simliar with an extra low quality 3Dlight render, where I just used the masking information. I'm not sure if the cameras still match up 1:1 with octane, but it worked fine for me back then.